Field of the Invention
The present invention generally relates to wireless communication networks, such as cellular networks. More particularly, the present invention relates to cellular networks based on OFDM access schemes (such as LTE/LTE-Advanced technology, WiMAX, WiFi and their evolutions) or CDMA access schemes, and to a method for efficiently and dynamically managing activation and deactivation of (e.g., small) nodes within such cellular networks.
Overview of the Related Art
Evolution of cellular networks has experimented a significant growth in terms of spread and performance, and has recently brought to 3GPP LTE (“Third Generation Partnership Project Long Term Evolution”)/LTE-Advanced standard.
3GPP LTE/LTE-Advanced standard is conceived for allowing data to be high-speed conveyed between a fixed-location transceiver base station or node (e.g., eNodeB) radiating radio waves over a respective land area (cell) and user equipments (e.g., user terminals, such as cellular phones) within the cell.
In order to optimize cellular networks performance (especially for unequal user equipments or data traffic distribution), 3GPP LTE/LTE-Advanced standardization activities have been addressed to heterogeneous scenarios - i.e. comprising both relatively high-power and wide-coverage nodes (or macro nodes), identifying so-called macro cells, and a number of lower-power, smaller-coverage nodes (or small nodes, e.g. micro, pico, femto nodes) identifying small cells within the macro cell for enhancing overall coverage and capacity thereby facilitating communication between user equipments within a macro cell and the pertaining macro node.
However, due to the growing number of mobile network users and to the growing demand for services requiring very high data traffic (such as multimedia and real-time services) and very limiting “Quality of Service”, multiple small nodes are typically deployed within each macro cell, in indoor and outdoor locations and anywhere high capacity is needed.
Thus, compared to traditional homogeneous cellular networks, which are based on macro nodes of comparable power and coverage, in heterogeneous cellular networks high density small nodes may also be deployed without full planning or even in entirely uncoordinated manner.
This can sharpen interference management and power consumption issues.
Interference may arise between the macro cell and the small cells, as well as between the small cells themselves.
In order to better manage the network capacity and performance, to reduce interference and optimize power consumption, scientific research (e.g., the standardization bodies like 3GPP) is considering to manage activation and deactivation of each small node according to traffic load (e.g., amount of data traffic and number of users equipments within the corresponding small cell).
Broadly speaking, small nodes can be activated for providing additional capacity, and deactivated when such additional capacity is no longer needed hence reducing power consumption—with such activation and/or deactivation that can be scheduled by the macro node or by the small nodes themselves.
In the state of the art, solutions are known aimed at controlling small nodes activation and deactivation.
EP 2512171 discloses a method for managing the state of micro nodes within a cellular network. The cellular network comprises a macro node containing a tracking area that covers micro cells (each one associated with a micro node). The method comprises activating the micro nodes within the tracking area, determining the number of user equipments in idle mode within the tracking area, and deactivating one or more micro nodes within the tracking area when the number of user equipments in idle mode is lower than a predetermined value. The method further comprises activating all the micro nodes within the tracking area if current load of the macro cell exceeds another predetermined value.
WO 2012/055984 discloses a cellular network comprising macro and small nodes, and a method for activating small nodes. The method comprises determining a current operational mode of a small node, switching the small node from inactive to more active operational modes upon fulfillment of predefined criteria (e.g., distance between user equipment and small node) and, according to current operational mode thereof, transmitting a corresponding switching signal from the macro node to the small node.
WO 2012/110075 discloses nodes wake-up control in heterogeneous network. For each node, average uplink interference, path-loss between node and neighboring nodes, and wake-up threshold interference of the neighboring nodes are retrieved for evaluating a wake-up condition. If the wake-up condition is satisfied, the node is switched from inactive (transmitter switched-off) to active (transmitter switched-on) states.